(CNN) -- Sen. John McCain took his weeklong environmental tour to Washington state Tuesday, addressing the need for reducing the nation's dependency on foreign oil and sparking investment in environmentally friendly technology.

McCain spoke at an environmental roundtable at Cedar River Watershed Education Center in North Bend, Washington.

Washington is among several potential battleground states in the West -- including California, Colorado, New Mexico, Nevada and Oregon -- where voters count the environment as a top issue.

McCain said Tuesday that coming up with new forms of clean energy is "a national security issue when we're dependent on more than $400 billion a year in imported oil from countries that don't like us very much ... some of that money is helping terrorist organizations."

The Arizona senator also said the heightened awareness of global environmental concerns could help push new forms of energy to the forefront of the nation's political agenda.

"Environment, national security and economy are all coming together, perhaps ... to spark ... an incredible impetus for us to sit down together, Republican and Democrat, environmentalists, business and bankers and retailers ... all together and address this problem."

McCain's commitment to fight global warming also puts him at odds with some Republicans in Congress and with the Bush administration, which has not made climate change a priority.

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"The president and I have disagreed on this issue for many years. It isn't a recent disagreement," he said.

When it comes to making his fellow GOP colleagues "mad in the past," McCain said his job is to "do what I know is best for this nation, particularly where our environment is concerned."

McCain also discussed nuclear energy -- namely the lack of investment in the controversial technology.

"Why is it that European countries have come up with solutions that people generally approve of? They have been able to reduce their greenhouse gas emissions," he said. "In the case of France, 80 percent of their electricity is generated by nuclear power."

McCain acknowledged the controversy surrounding nuclear technology -- including the "billions we've spent already trying to clean it [nuclear waste] up ... It's staggering and we have a whole lot more to do."

"If other countries are able to make use of nuclear power ... I don't know why the United States of America can't."

On Monday, McCain delivered a speech outlining his vision for combating global warming.

"We stand warned by serious and credible scientists across the world that time is short and the dangers are great," McCain said in Portland, Oregon. "The most relevant question now is whether our own government is equal to the challenge."

McCain's stance on carbon emissions places him closer on the environmental spectrum to the Democratic candidates, Sens. Barack Obama and Hillary Clinton.

But some evangelicals, a vital voting bloc for Republicans, are warming up to McCain's plan.

The Rev. Jim Ball, a spokesman for the Evangelical Climate Initiative, issued a press release after McCain's speech Monday. Ball said the group is "greatly encouraged by the principles and proposals."

"We consider the decisions we make about energy to be at their root moral choices, as Christians we commend the speech's moral high road. ... Sen. McCain's support of strong policy on emissions is in line with the evangelical community."

In his speech Monday, the presumed GOP nominee proposed capping carbon emissions incrementally, with the goal of returning to 1990 emission levels by the year 2020 using a cap-and-trade program.

Such a program would cap greenhouse gas emissions at certain levels, and allow more efficient energy producers to sell emissions permits to other, less efficient companies, thereby creating market-wide incentives to reduce carbon output.

According to McCain's campaign Web site, "He has offered common-sense approaches to limit carbon emissions by harnessing market forces that will bring advanced technologies, such as nuclear energy, to the market faster, reduce our dependence on foreign supplies of energy and see to it that America leads in a way that ensures all nations do their rightful share."

McCain said this system will encourage companies to seek more efficient means of production.

McCain also released a television ad Monday in Oregon that connects climate change to increased destructive weather phenomena like hurricanes. The spot features a McCain voiceover: "It's not just a greenhouse gas issue, it's a national security issue." Watch the ad »

This week, the Democratic National Committee accused McCain of hypocrisy on the energy issue, e-mailing reporters a list of McCain advisers who have served as lobbyists for the oil industry.

Before McCain's Monday speech, DNC Chairman Howard Dean called McCain the wrong choice for voters who want "a true champion of the environment."

"Sen. McCain is once again trying to re-cast himself as a friend of the environment for the general election, but his record clearly shows that the only friends he really stands up for are his donors and the lobbyists running his campaign," Dean said in a statement. "No campaign rhetoric can change his record."